IMPORTANT TO KNOW!
--DAY ONE--
WIRELESS STANDARDS
--802.11 notes--
*Managed by IEEE LAN/MAN standards committee
*Wifi alliance handles interoperability testing
--802.11a-- (wifi 1)
*launched 1999
*operates in 5ghz range
*it can use other frequencies with special licensing
*54 megabits per second
*Smaller range than 802.11b
*high frequency is absorbed by objects on the way
--802.11b-- (wifi 2)
*Also launched in 1999
*Operates in 2.4ghz
*11 megabits per second
* better range than 802.11a(Less absorbtion problems)
*more frequent conflict(baby monitor, cordless phone,bluetooth)-not commontly seen today
--802.11g-- (wifi 3)
*An upgrade from 802.11b
*launched june 2003
*operates in the 2.4 ghz range
*54 megabits per second ( similar to 802.11a)
*backwards compatible with 802.11b
*same 2.4 ghz frequency conflict problems as 802.11b
--802.11n (wifi 4)
*The update from 802.11a,802.11b,802.11g
*launched october 2009
*operates at 5ghz and/or 2.4 ghz (40 mHz channel width)
*600 megabits per second ( 40 mHz mode with 4 antennas)
*802.11n uses MIMO (Multiple input-Multiple output)(multiple transmit and receive antennas
--802.11ac (wifi 5)
*Approved in January 2014 *Significant improvements over 802.11n
*operates in the 5Ghz band
*Less crowded, more frequences(up to 160Mhz channel bandwitdth)
*Increased channel bonding (Larger bandwidth usage)
*Denser signaling modulation(faster data transfers)
*Eight Mu-Mimo downlink streams
*Twice as many streams as 802.11n
*Nearly 7 gigabits per second
--802.11ax-- (wifi 6)
*Approved in February 2021
*The successor to 802.11ac/wifi 5
*Operates at 5Ghz and/or 2.4Ghz
*20,40,80 and 160 Mhz channel width
*1,201 mrgabits per second per channel
*A relatively small increase in throughput
*Eight Bi-Directional MU-MIMO streams
*Orthogonal frequency-division multiple access
*Works similar to cellular communication
*Improves high density installations
--Functions of MDM (Mobile device management)-- *Device configuration - Remotely set device settings like passwords,security policies,wifi connectors and app restrictions.
*Application management - Conttrol which apps can be installed and updated on devices including white/blacklisting specific apps
*Security updates - Push out security patches and OS updatges to device automatically
*Data protection - Remotely wipe sensitive data from lost pr stolen devices
*Device tracking - Locate lost devices using GPS capabilities *compliance monitoring -Ensure devices adhere to comapany policies and industry regulations
HTTP - HYPERTEXT TRANSFER PROTOCOL/PORT 80 (web browser/web server)
HTTPS - HYPERTEXT PROTOCOL SECURE/PORT 443 (web browser/we server)
SSL - SECURE SHELL/PORT 22 (secure remote access)
FTP - FILE TRANSFER PROTOCOL/PORT 21 (transfering of files)
SMTP - SIMPLE MAIL TRANSFER PROTOCOL/PORT25 (sending mail messages/outbound)
DNS - DOMAIN NAME SYSTEM/PORT 53 (dns client-dns server)
POP3 - POST OFFICE PROTOCOL VERSION 3/PORT 110 (retrieve mail from server)
IMAP - INTERNET MESSAGE PROTOCOL/PORT 143 (access and manage stored emails)
RDP - REMOTE DESKTOP PROTOCOL/PORT3389 (remote access and control other devices)
TELNET - PORT 23 (execute commands on its commandline)
NTP - NETWORK TIME PROTOCOL/PORT 123 (accurate time/date)
BGP - BORDER GATEWAY PROTOCOL/PORT 179 (used by routers to exchange routing information)
ISAKMP - INTERNET SECURITY ASSOCIATION AND KEY MANAGEMENT PROTOCOL/PORT 500 (establishes secure vpn tunnel)
LDAP - LIGHTWEIGHT DIRECTORY ACCESS/PORT 389 (usernames, passswords & other details stored)
SIP - SESSION INITIATION PROTOCOL/PORT 5060/5061 (channel for voip call on pc and mobile)
SYSLOG - PORT 514 (way to convert system event logs from various sources in a network)
-- RAID -- (REDUNDANT ARRAY OF INDEPENDENT DISKS)
*They're also inexpensive disks
*different Raid levels
*Some redundant, Some not
-- RAID 0 -- (STRIPING)
*File blocks are split between two or more physocal drives
*High performance
*data written quickly
*No redundancy
*A drive failure breaks the array
*RAID 0 is ZERO redundancy
-- RAID 1 -- (MIRRORING)
*File blocks are duplicated between two or more physical drives
*High disk utilization
*Every file is duplicated
*Required disk space is doubled
*High redundancy
*Drive failure does not affect data availability
-- RAID 5 -- (Striping with Parity)
*File blocks are striped
*Along with parity block
*Requires atleast three disks
*Efficient use of disk space
*Files aren't duplicated, but space is still used for parity
*High redundancy
*Data is available after drive failure
*parity calculation may affect performance
-- RAID 10(1+0) -- (A stripe with mirrors)
*The speed of striping, The redundancy of mirroring
*The bet of both worlds
*Need atleast 4 drives
-- DAY TWO --
Difference between LCD,LED & OLED- AMOLED & MINI-LED
*Mini LED - Utilizes smaller LED backlights fro improved brightness and dimming compared to standard LED/LCD.
*LCD - Displays use a backlight to illuminate liquid crystals
-Liquid crystal display/Used liquid crystal display to control the amount light passing through a backlighyt, Creating an image on the screen
*LED - Displays use of LED lights as the backlight for an LCD panel
-Light emitting diode/provides better color accuracy and energy efficiency comapred to older LCD backlights
*OLED - Displays have individual pixels that emit their own light, allowing for much deeper blacks and superior contrast compared to LCD and LED technologies/Excellent viweing angles
-Organic light emitting diode
*AMOLED - Active matrix light emitting diode(often seen in smartphones, high refresh rates & fast response times
-Inverter is a device that converts direct current power(DC)from a battery into alternating current(AC) Power, which is a type of power most households appliance need to function
-Rectify/Rectifier change AC to DC = Straightens the direction of thr current by allowing it to flow only one direction\
*CPU - Central processing unit is the main component of a computer that controls the flow of data and instructions also known as thr main processor
--SCREEN FAILURES--
*Lid switch problem, Loose connection, Video adapter, Inverter problem, flex connector, the display itself, power connection
--KEYBOARD FAILURES-- * Sticky keys, Damaged keyboard, Loose connection
--CONNECTORS--
*Flex connector - Connection used in piping systems to absorb variation
*SATA CABLES - Used for connecting drives
-15pin is the power & 7pin is for data
*SO-DIMM - Small outline dual in line memory module
-smaller version of a standard DIMM used primarily in laptops and other compact devices where space is limited
*Regular standard DIMM - Used for desktops
-Bigger in size & requires more space
-Random access memory (RAM)
-- CELLULAR CARDS --
*WWAN : WIRELESS WIDE AREA NETWORK
-These can be informal or external
-M.2 is prefered form factor as it offers 4G network connectvity
-M.2 size is 2230 (22mm Wide & 30mm LOng)
-M.2 used to be called next generation form factor (NGFF)
-USB is a common external option(Try 3.0 blue ports/better)
-Express cards & PCMCIA Cards can help get celluar network in older laptops
-These cards typically have one notch
*For Wifi and Bluetooth, M.2 combo cards are common which have two noyches comapred to a cellular card.
-Check compatibility to install these
-Two connectors for antenna's
-WLAN auto config & bluetooth support services
*A PCIe Card
-Peripheral component interconnect express card
-An expansion card tha connects to a computer's motherboard using a PCIe slot, allowing users to add functionalities like graphics processing, networking, storage or other capabilities not
already intergrated into the motherboard itself - essentially a way to upgrade or add features to a computer by plugging in a specialised card into a dedicated slot.
*COMMON USES ARE :
-Graphics card: For enhaced gaming or professional graphics applications
-Network adapters: To improve network connectivity
-Solid state drive: For faster storage options
-- DAY THREE --
COMAPRE AND CONSTRAST MOBILE DEVICES - TABLETS
*IPS(IN PLANE SWITCHING) - Allows for wider viewing in tablets
*Quad extended graphics Array(QXGA) - Has a esolution of 2048(across) x 1536(width)
*4:3 Aspect ratio(Has a little more space & height)
*1.85 Ghz ARM-BASED CPU (Advanced risk machine) lower performance
*LPDDR4 RAM(LOWER POWER DOUBLE DATA RATE)
-8.827Mah
-32.4 watt/hour (these two mean 10 hours of typical use max for battery)
MOBILE DEVICES -6.0 INCH(18:9)
-2880 x 1440
*2.45 ARM BASED CPU (SNAPDRAGON 835)(64BIT SYSTEM ON A CHIP)
*4GB LPDDR4 RAM
*32,64.128 OR 256 GB flashing memory(Similar to SDDs)
*Multitouch screen(Capacitive screen)
*Lithium-ION polymer battery
WEARABLE TECHNOLOGIES
*SMART WATCHES, HEADPHONES, FITNESS TRACKERS, GLASSES, SMARTPHONES, SMART SHOES, RING, CLOTHES.
-- WIRELESS CONNECTIONS --
*Bluetooth -Includes headsets, earbuds, smartwatches & more
-Class two is the most common allowing for communications up to 33 feet.
-Uses the 2.4Ghz -Unlincesed ISM(INDUSTRIAL,SCIENTIFIC AND MEDICAL)BAND.
-Same as 802.11
-Short range, Most consumer devices operate to about 10meters
-Indystrial bluetooth can communicate over 100 meters
*NFC (NEAR FIELD COMMUNICATON) via radio frequency/touch devices together
-Allows for close proximity communication with encryption support
-13,56MHz (Slower than bluetooth) 100 - 400 kb/s.
-Two way wireless communication
-Builds on RFID, Which is mostly one way.(RADIO FREQUENCY IDENTIFICATION)
-payment systems, Online wallets & major credit cards.-Bootstrap for other wireless devices
-Helps with bluetooth pairing
-Access token identity card
*IR (INFRARED) Smartphones/Tablets
-IR blasters were common for a long time
-Abandoned by many companies in 2017
*Mobile Hotspot (Wireless)
-Allows other systems to share the smartphones internet connection
-Can incur fees!
*USB TETHERING
-Sharing wired internet connection
-Wifi is disabled during Tether
--PROTECTING A PHONE--
*Insurance , Anti-Malware, Encryption, Locator programs, Remote wipe programms
** NOTE: WE HAVE A HOST & PERIPHERAL DEVICES **
-Host: Controlling other devices
-Peripheral: Being controlled by other devices(Depending on the connection)
*OTG - DEVICES THAT CAN OPERATE AS A HOST OR PERIPHERAL
-- MOBILE EMAIL --
PROTOCOL - ORIGINAL PORT - SECURE PORT
-SMTP 25 456/587 -POP3 110 995 (Makes use of SSL(Secure socket layer)
-IMAP 143 993(Makes use of TLS( Transport layer security)
*The two are security features on port 995/993
-- SECURITY TYPE --
*SSL
-Less secure than TLS
-Used to encrypt data transmitted over the internet
-Developed by Netscape
-Port 443
*TLS
-More secure than SSL
-Addresses security vulnerabilities present in the older SSL protocols
-Used to encrypt data transmitted over the internet
-Enhanced security features
-Port 443
-- DAY FOUR --
RADIO AND ID
*At first cellphones used GSM (Global system for mobile communication) for voice calls and GPRS for sending/transmitting data
-Then Edge was used to attain 3G speeds.
-4GB and LTE speeds are possible with IMT-Advanced requirement.(International mobile telecommunications enhanced)
-5G is currently being deployed(ITU IMT - 2020 STANDARD, 20GB/S)
-Airplane mode disables any and all of these (3G,4G,5G,LTE & EDGE)
*PRL (PREFFERED ROAMING LIST)
-A DB of service provider radio information
-Used with CDMA networks
*Baseband updates
-Used with GSM
-Also called Radio firmware
-Without a connection to a cell tower, Updates can not be done
*ISP (Internet service provider)
*IMEI (International mobile station equipment identity)
*CDMA (Code division multiple access)
*IMSI (International mobile subscriber identity)
*SIM (Subscriber identity module)
*GPRS (General packet radio dervice
Difference between PRIVATE & PUBLIC IP ADDRESS
*PRIVATE IP ADDRESS
-Used within a local network(Home office)
-Not accesible from the internet
*Provides security by keeping internal traffic private
*PUBLIC IP ADDRESS
-Assigned by ISP
-Unique and accessible from anywhere on the internet
*Used to access websites and online services
-- SYNCHRONISATION METHODS --
*SYNC to cloud ( Google drive, Dropbox, One drive) uploading files to be accessible
*Mutual authentication for multiple services ( using gmail to sync all app information)
*SYNC to desktop/Laptop
-Usually done by USB
-Often requires an MTP connection done by USB MTP(Media transfer protocol) PTP(Photo transfer protocol)
-SYNC between mobile devices
*Can be done via OTG USB or Via WIFI Or NFC
*Software requirements to install sync apps to PC(Make sure your system is compatible to install these applications)
*SYNC to automobile - Using your vehocle to access your device info like calls , music, photos and messaging
-- DNS ( DOMAIN NAME SYSTEM) --
* Converts names to IP addressed & Vice versa
-Usually managed by ISP or enterprise IT department (A critical source)
-- DHCP (Dynamic Host configuration Protocol) --
*Automatic IP address configuration
*Very common service ( available on most home routers)
*Enterprise DHCP will be redundant (Usually running on cemtral servers)
-- File server --
* Centralised storage of documents, spreadseets, videos, pictures and any other file(A fileshare)
*Standard system of file management.
-SMB(Server message block) Apple filing protocol(AFP)etc.
*The front end hides the protocol(Copy, delete, rename etc.
-- Print Server --
*Connect a printer to the network(Provide printing services for all network devices)
*May be software in a computer(computer is connected to a printer)
*May be built in to the printer(Network adapter and software)
*Uses standard printing protocols(SMB server message block)
*IPP(Internet printing protocol)
*LDP(Line printer Daemon)
-- MAIL SERVER --